Fundamental relations for the velocity dispersion of stars in the Milky Way
(2021) In Monthly Notices of the Royal Astronomical Society 506(2). p.1761-1776- Abstract
We explore the fundamental relations governing the radial and vertical velocity dispersions of stars in the Milky Way, from combined studies of complementary surveys including GALAH, LAMOST, APOGEE, the NASA Kepler and K2 missions, and Gaia DR2. We find that different stellar samples, even though they target different tracer populations and employ a variety of age estimation techniques, follow the same set of fundamental relations. We provide the clearest evidence to date that, in addition to the well-known dependence on stellar age, the velocity dispersions of stars depend on orbital angular momentum Lz, metallicity, and height above the plane |z|, and are well described by a multiplicatively separable functional form. The dispersions... (More)
We explore the fundamental relations governing the radial and vertical velocity dispersions of stars in the Milky Way, from combined studies of complementary surveys including GALAH, LAMOST, APOGEE, the NASA Kepler and K2 missions, and Gaia DR2. We find that different stellar samples, even though they target different tracer populations and employ a variety of age estimation techniques, follow the same set of fundamental relations. We provide the clearest evidence to date that, in addition to the well-known dependence on stellar age, the velocity dispersions of stars depend on orbital angular momentum Lz, metallicity, and height above the plane |z|, and are well described by a multiplicatively separable functional form. The dispersions have a power-law dependence on age with exponents of 0.441 ± 0.007 and 0.251 ± 0.006 for σz and σR, respectively, and the power law is valid even for the oldest stars. For the solar neighbourhood stars, the apparent break in the power law for older stars, as seen in previous studies, is due to the anticorrelation of Lz with age. The dispersions decrease with increasing Lz until we reach the Sun's orbital angular momentum, after which σz increases (implying flaring in the outer disc) while σR flattens. For a given age, the dispersions increase with decreasing metallicity, suggesting that the dispersions increase with birth radius. The dispersions also increase linearly with |z|. The same set of relations that work in the solar neighbourhood also work for stars between 3 < R/kpc < 20. Finally, the high-[α/Fe] stars follow the same relations as the low-[α/Fe] stars.
(Less)
- author
- organization
- publishing date
- 2021-09-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Galaxy: disc, Galaxy: evolution, Galaxy: formation, Galaxy: kinematics and dynamics
- in
- Monthly Notices of the Royal Astronomical Society
- volume
- 506
- issue
- 2
- pages
- 16 pages
- publisher
- Oxford University Press
- external identifiers
-
- scopus:85112213212
- ISSN
- 0035-8711
- DOI
- 10.1093/mnras/stab1086
- language
- English
- LU publication?
- yes
- id
- 0fade640-e958-49c7-8686-f8485c6970a5
- date added to LUP
- 2021-09-14 12:33:37
- date last changed
- 2024-04-20 12:14:38
@article{0fade640-e958-49c7-8686-f8485c6970a5,
abstract = {{<p>We explore the fundamental relations governing the radial and vertical velocity dispersions of stars in the Milky Way, from combined studies of complementary surveys including GALAH, LAMOST, APOGEE, the NASA Kepler and K2 missions, and Gaia DR2. We find that different stellar samples, even though they target different tracer populations and employ a variety of age estimation techniques, follow the same set of fundamental relations. We provide the clearest evidence to date that, in addition to the well-known dependence on stellar age, the velocity dispersions of stars depend on orbital angular momentum Lz, metallicity, and height above the plane |z|, and are well described by a multiplicatively separable functional form. The dispersions have a power-law dependence on age with exponents of 0.441 ± 0.007 and 0.251 ± 0.006 for σz and σR, respectively, and the power law is valid even for the oldest stars. For the solar neighbourhood stars, the apparent break in the power law for older stars, as seen in previous studies, is due to the anticorrelation of Lz with age. The dispersions decrease with increasing Lz until we reach the Sun's orbital angular momentum, after which σz increases (implying flaring in the outer disc) while σR flattens. For a given age, the dispersions increase with decreasing metallicity, suggesting that the dispersions increase with birth radius. The dispersions also increase linearly with |z|. The same set of relations that work in the solar neighbourhood also work for stars between 3 < R/kpc < 20. Finally, the high-[α/Fe] stars follow the same relations as the low-[α/Fe] stars. </p>}},
author = {{Sharma, Sanjib and Hayden, Michael R. and Bland-Hawthorn, Joss and Stello, Dennis and Buder, Sven and Zinn, Joel C. and Kallinger, Thomas and Asplund, Martin and De Silva, Gayandhi M. and D'Orazi, Valentina and Freeman, Ken and Kos, Janez and Lewis, Geraint F. and Lin, Jane and Lind, Karin and Martell, Sarah and Simpson, Jeffrey D. and Wittenmyer, Rob A. and Zucker, Daniel B. and Zwitter, Tomaz and Chen, Boquan and Cotar, Klemen and Esdaile, James and Hon, Marc and Horner, Jonathan and Huber, Daniel and Kafle, Prajwal R. and Khanna, Shourya and Ting, Yuan Sen and Nataf, David M. and Nordlander, Thomas and Saadon, Mohd Hafiz Mohd and Tepper-Garcia, Thor and Tinney, C. G. and Traven, Gregor and Watson, Fred and Wright, Duncan and Wyse, Rosemary F.G.}},
issn = {{0035-8711}},
keywords = {{Galaxy: disc; Galaxy: evolution; Galaxy: formation; Galaxy: kinematics and dynamics}},
language = {{eng}},
month = {{09}},
number = {{2}},
pages = {{1761--1776}},
publisher = {{Oxford University Press}},
series = {{Monthly Notices of the Royal Astronomical Society}},
title = {{Fundamental relations for the velocity dispersion of stars in the Milky Way}},
url = {{http://dx.doi.org/10.1093/mnras/stab1086}},
doi = {{10.1093/mnras/stab1086}},
volume = {{506}},
year = {{2021}},
}